The present invention relates to detecting environmental contamination and more particularly, to detecting such contamination in the vadose soil zone.
The production, distribution, use, misuse, disposal, or accidental spills of many chemicals have polluted some environments to levels that threaten the health of humans, livestock, wildlife and, indeed, whole ecosystems. Most of these chemicals, or contaminants, are produced to improve human health, standards of living, and safety through advancements in manufacturing, agriculture and agribusiness, medicine, and to strengthen national defense. Ironically, their unplanned intrusions into the environment can have an adverse effect in direct contrast with their intended benefits.
In many countries, such as the United States, efforts to manage and measure the extent and level of the presence of these contaminants in the environment have resulted in many laws and regulations that prescribe, and proscribe, a variety of measures. Environmental site characterizations are usually one of the earliest steps in trying to identify and model pollution and contamination at a potential site. These site characterizations can include many aspects of the environments such as soil, air and water. Two common ways to characterize soil contamination include profiling the soil using core samples taken throughout the depth of a region and taking near-surface soil samples over a wide area.
Near-surface soil sampling has the significant drawback that soil at this depth is far from uniform in many, if not all, locations. The variability of soil type, texture and organic content impact both the reliability and the confidence of any characterization of soil contamination using this method. Soil profiles over a the entire depth of a soil layer are usually performed using grid drilling methods. Profiling the soil in this manner is very expensive, very slow, and invasive to the area.
Once an area has been determined to be contaminated, a number of methods for cleaning the site are available and many more are in the process of being developed. One area that has shown much promise and acceptance is using surface vegetation for bioremediation to assist in the cleaning-up of a site which is determined (such as through soil characterization) to be contaminated. Bioremediation describes several technologies and practices that take advantage of natural systems and processes to clean up pollution. These technologies entail the science of understanding natural processes that promote and accelerate destruction, transformation, removal, or stabilization of pollutants. The practice of bioremediation involves implementation and management of strategies that enhance these processes. Successful bioremediation strategies are those that are tailored to satisfy specific pollutant, site, public, regulatory, cost-effectiveness, and environmental-effectiveness considerations. Thus, bioremediation, while very useful, is a technology that is implemented only after a site is determined to be contaminated.
Independent of the above concerns, vegetation analysis has been used in the mining and petroleum industries to outline areas with near-surface enrichment of various compounds suggesting underlying deposits of interest. However, in these industries, the underlying deposits have had a time-frame of geological proportion to permeate upwards and affect both the soil and the vegetation growing in that soil. Also, these naturally occurring xe2x80x9cmarkerxe2x80x9d compounds are different than man-made contaminants which can render a site unhealthy. Specifically, these xe2x80x9cmarkerxe2x80x9d compounds are typically naturally occurring metals or relatively light hydrocarbons that are easy to detect.
There is a need, therefore, unmet by all the prior processes and procedures discussed above, for a method of quickly, inexpensively, and non-invasively determining areas of the vadose soil zone which are contaminated with contaminants that adversely impact the environment and that may have been in the sub-surface soil for only a relatively short period of time.
The present invention addresses and meets these and other needs by analyzing vegetation samples obtained from the surface of a region to determine whether the vadose soil zone of that region is contaminated. In particular, one aspect of the present invention relates to a method for performing exploration of the vadose soil zone by obtaining samples of the surface vegetation from a region, analyzing the samples to determine if a contaminant is present in the analyzed samples, and determining if a vadose soil zone at that region is contaminated based on the analyzed samples.
Another aspect of the present invention relates to a method for performing soil contaminant exploration which includes the step of determining the sub-surface contamination of a region by performing analysis on a plurality of surface vegetation samples of the region.
A still further aspect of the present invention relates to a method for performing soil contaminant exploration which includes the steps of determining the sub-surface contamination of a region by performing analysis on a plurality of surface vegetation samples of the region, and selecting that region for additional soil contamination characterization based on the analysis of the surface vegetation samples.
Yet another aspect of the present invention relates to a method for contaminant exploration that includes the step of determining whether or not an aquifer below a vadose soil zone of a region is contaminated by performing analysis on a plurality of surface vegetation samples from that region.